Maraakate
Veteran Member
Hey everyone,
I've been having some problems this season with the 550 holding a good idle. When the bike is cold, runs and idles quite well, but after about 5-10 minutes when it's warmed the spark starts cutting out at idle it appears and then I have to keep blipping the throttle here and there. When actually moving it drives great.
I've cleaned the carbs multiple times years ago, new OEM float needles and OEM gaskets/o-rings, including intake. So with all that said, I decided to do a compression test and all 4 cylinders are within 5 psi of each other (did this while mildly cold, bike sat after a 10 minute ride for a couple of hours). Didn't take exact readings but they were about 150-155psi. So the engine is in pretty decent shape and valves are probably adjusted OK. I adjusted the valves last season before putting the bike in storage.
When I took the plugs off, 3 of the 4 were whitish with deposits, indicating a lean condition. The fourth plug was a bit sooty. One of the plugs the gap was a bit wider than the others so I fixed the gap on it. Wasn't extreme, but enough to notice.
I grabbed a large truck battery that was fully charged, hooked it up to the bike, started it up with a timing light and just watched as it idled. What I found is that the ignition is too advanced (I forget the marks will attach a picture below, I always get this part confused as I don't do it enough) I believe. It's not at the 'F' marks for the appropriate cylinders. It's quite a bit more forward. If I recall, two years ago it was a bit off the 'F' mark but not extreme and now I remember that I couldn't get those screws out in order to rotate the plate to change it. 2-3 seems to bounce a bit between two points which could indicate a problem with that particular coil or possibly points or condenser. And yes, changed the inductive clamp on one side of the plug cap vs the other to make sure. It's the same in either direction.
At this point I've tried:
I'm thinking I may need to get a real JIS bit for my impact. Usually my impact will get the stuff out, but this was starting to round it slightly and I stopped using it. The screws are still in good shape and the JIS tools fit in it so I don't want to muck that up. Anyone have advice on this? I'm guessing they have never been adjusted before and if it's too advanced then maybe that's why the plugs were whitish with some white buildup on the plug and maybe it's why my idle starts cutting out once the bike is warmed up. My plan is to just keep coming back every now and again and spraying penetration fluid on it and maybe it will eventually come out. It's pretty clean in there, so I think it's just all the heat/cool cycles over 40+ years.
I've attached a picture of the marks from the book. It's quite a bit off, I've marked where I think it generally is in red. Can someone confirm that means I'm too advanced? I always forget the rotation and how that works.
NB: Please don't tell me to take this thread to SOHC4. Not a big fan of that place for various reasons I won't get into here.
I've been having some problems this season with the 550 holding a good idle. When the bike is cold, runs and idles quite well, but after about 5-10 minutes when it's warmed the spark starts cutting out at idle it appears and then I have to keep blipping the throttle here and there. When actually moving it drives great.
I've cleaned the carbs multiple times years ago, new OEM float needles and OEM gaskets/o-rings, including intake. So with all that said, I decided to do a compression test and all 4 cylinders are within 5 psi of each other (did this while mildly cold, bike sat after a 10 minute ride for a couple of hours). Didn't take exact readings but they were about 150-155psi. So the engine is in pretty decent shape and valves are probably adjusted OK. I adjusted the valves last season before putting the bike in storage.
When I took the plugs off, 3 of the 4 were whitish with deposits, indicating a lean condition. The fourth plug was a bit sooty. One of the plugs the gap was a bit wider than the others so I fixed the gap on it. Wasn't extreme, but enough to notice.
I grabbed a large truck battery that was fully charged, hooked it up to the bike, started it up with a timing light and just watched as it idled. What I found is that the ignition is too advanced (I forget the marks will attach a picture below, I always get this part confused as I don't do it enough) I believe. It's not at the 'F' marks for the appropriate cylinders. It's quite a bit more forward. If I recall, two years ago it was a bit off the 'F' mark but not extreme and now I remember that I couldn't get those screws out in order to rotate the plate to change it. 2-3 seems to bounce a bit between two points which could indicate a problem with that particular coil or possibly points or condenser. And yes, changed the inductive clamp on one side of the plug cap vs the other to make sure. It's the same in either direction.
At this point I've tried:
- One of those Vessel brand screwdrivers that claims to be JIS (not quite JIS I've noticed, but pretty close usually works 90% of the time get the screws out)
- The actual JIS screw that came in the tool bag
- Taking the tool bag screwdriver and putting a pair of pliers on the handle
- Taking a mini sledge to the handle of the Vessel screwdriver as I turn it either direction.
- Spraying penetrating fluid in each of these 3 screws multiple times (making sure to put a rag over the points)
- Using a butane torch over the screws (this approach didn't work as well, doesn't seem to get hot enough)
I'm thinking I may need to get a real JIS bit for my impact. Usually my impact will get the stuff out, but this was starting to round it slightly and I stopped using it. The screws are still in good shape and the JIS tools fit in it so I don't want to muck that up. Anyone have advice on this? I'm guessing they have never been adjusted before and if it's too advanced then maybe that's why the plugs were whitish with some white buildup on the plug and maybe it's why my idle starts cutting out once the bike is warmed up. My plan is to just keep coming back every now and again and spraying penetration fluid on it and maybe it will eventually come out. It's pretty clean in there, so I think it's just all the heat/cool cycles over 40+ years.
I've attached a picture of the marks from the book. It's quite a bit off, I've marked where I think it generally is in red. Can someone confirm that means I'm too advanced? I always forget the rotation and how that works.
NB: Please don't tell me to take this thread to SOHC4. Not a big fan of that place for various reasons I won't get into here.